Aryl acetate onium materials

ABSTRACT

Acid generators comprising a carbocyclic aryl or heteroaromatic group substituted with at least one acetate moiety are provided. These acid generators are particularly useful as a photoresist composition component.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S.patent application Ser. No.14/040,594, filed Sep. 27, 2013. The contents of the foregoingapplication is incorporated herein by reference in its entirety.

FIELD

In one aspect, the present invention relates to new onium acidgenerators that comprise a carbocyclic aryl or heteroaromatic groupsubstituted with at least one acetate moiety.

INTRODUCTION

Photoresists are photosensitive films for transfer of images to asubstrate. They form negative or positive images. After coating aphotoresist on a substrate, the coating is exposed through a patternedphotomask to a source of activating energy such as ultraviolet light toform a latent image in the photoresist coating. The photomask has areasopaque and transparent to activating radiation that define an imagedesired to be transferred to the underlying substrate. A relief image isprovided by development of the latent image pattern in the resistcoating.

Known photoresists can provide features having resolution and dimensionsufficient for many existing commercial applications. However for manyother applications, the need exists for new photoresists that canprovide highly resolved images of submicron dimension.

Various attempts have been made to alter the make-up of photoresistcompositions to improve performance of functional properties. Amongother things, a variety of photoactive compounds have been reported foruse in photoresist compositions. See US 20070224540 and EP 1906241. Seealso U.S. Pat. No. 8,318,403 and US 2012/0015299. Short-wavelengthimaging also has been utilized, such as 193 nm. Extreme ultraviolet(EUV) and e-beam imaging technologies also have been employed. See U.S.Pat. No. 7,459,260. EUV utilizes short wavelength radiation, typicallybetween 1 nm to 40 nm, with 13.5 nm radiation often employed.

EUV photoresist development continues to be a challenging issue for EUVLithography (EUVL) technology implementation. Required are developmentof materials that can provided highly resolved fine features, includinglow linewidth roughness (LWR), and sufficient sensitivity to affordwafer throughput.

SUMMARY

We have now discovered new acid generators and photoresist compositionsthat comprise one or more of such acid generators.

In one aspect, acid generators are provided that comprise a carbocyclicor heteroaromatic group substituted with at least one acetate moiety.

Particularly preferred acid generators may comprise a diester moietyrepresented by a structure of the formula:—Y—C(═O)O(CX′X″₂)_(n)C(═O)ORin which Y is a linker comprising one or more carbon atoms (such as a—CH₂— group), provided that Y is unsubstituted by non-hydrogensubstituent(s);

n is a positive integer;

each X′ and X″ is independently a hydrogen or non-hydrogen substituent;and

R is a non-hydrogen substituent such as optionally substituted alkyl,optionally substituted heteroalkyl, optionally substituted alicyclic,optionally substituted heteroalicyclic, optionally substitutedcarbocyclic aryl or optionally substituted heteroaromatic.

In certain preferred aspects, the acid generator comprises a structureof Formula (I):

wherein

-   -   Z is a counter anion, such as a non-nucleophilic anion (e.g.,        carboxylate, sulfate, sulfonate, sulfamate, or the anion of a        sulfonamide or sulfonimide);    -   X is sulfur or iodine;    -   R is hydrogen or a non-hydrogen substituent such as optionally        substituted alkyl, optionally substituted heteroalkyl,        optionally substituted alicyclic, optionally substituted        heteroalicyclic, optionally substituted carbocyclic aryl or        optionally substituted heteroaromatic;    -   R′ and R″ are the same or different non-hydrogen substituents        such as optionally substituted alkyl, optionally substituted        heteroalkyl, optionally substituted alicyclic, optionally        substituted heteroalicyclic, optionally substituted carbocyclic        aryl or optionally substituted heteroaromatic, and optionally        may form a ring, provided that if X is iodine, one of R′ and R″        is absent; and    -   A is an optionally substituted carbocyclic aryl or optionally        substituted heteroaromatic group (e.g., a C₆₋₁₄ carbocyclic aryl        or optionally substituted heteroaromatic group having from 5 to        14 atoms, including 1-4 heteroatoms selected from O, S, and N,        in the heteroaromatic ring system).    -   In certain embodiments of Formula (I), X is sulfur.    -   In certain preferred aspects, the acid generator comprises a        structure of Formula (II):

wherein Z is a counter anion, such as a non-nucleophilic anion (e.g.,carboxylate, sulfate, sulfonate, sulfamate, or the anion of asulfonamide or sulfonimide);

R is hydrogen or a non-hydrogen substituent;

each T, each T′ and each T″ are the same or different non-hydrogensubstituent, wherein either of T and T″ or T and T′ are capable ofjoining to form a ring;

n is 0, 1, 2, 3 or 4;

n′ and n″ are each independently 0, 1, 2, 3, 4 or 5;

J represents a chemical bond, or a group capable of covalently linking Band C; and

A, B, and C are each the same or different optionally substitutedcarbocyclic aryl or optionally substituted heteroaromatic groups (e.g.,C₆₋₁₄ carbocyclic aryl or heteroaromatic group having from 5 to 14atoms, including 1-4 heteroatoms selected from O, S, and N, in theheteroaromatic ring system).

In certain preferred aspects, the present acid generators are oniumcompounds, such as iodonium or sulfonium materials, with sulfonium acidgenerators being generally preferred.

In certain preferred aspects, the acid generator comprises a structureof Formula (IIa):

wherein Z is a counter anion;

R is hydrogen or a non-hydrogen substituent;

each T, each T′ and each T″ are the same or different non-hydrogensubstituent, wherein either of T and T″ or T and T′ are capable ofjoining to form a ring;

n is 0, 1, 2, 3 or 4;

n′ and n″ are each independently 0, 1, 2, 3, 4 or 5;

R^(a) and R^(b) are each H, or R^(a) and R^(b) taken together representa chemical bond or a group capable of covalently linking B and C; and

A, B, and C are each the same or different optionally substitutedcarbocyclic aryl or optionally substituted heteroaromatic groups.

Particularly preferred acid generators include those of the followingFormula III:

wherein T, T′, T″, J, n, n′, n″ and Z are as defined for Formula (II), Ais a phenyl ring, and R is hydrogen or a non-hydrogen substituent.

Further preferred acid generators include those of the following FormulaIIIa:

wherein:

Z is a counter anion;

each T, each T′ and each T″ are the same or different non-hydrogensubstituent, wherein either of T and T″ or T and T′ are capable ofjoining to form a ring;

n is 0, 1, 2, 3 or 4;

n′ and n″ are each independently 0, 1, 2, 3, 4 or 5;

R^(a) and R^(b) are each H, or R^(a) and R^(b) taken together representa chemical bond or a group capable of covalently linking B and C; and

B and C are the same or different optionally substituted carbocyclicaryl group.

Further preferred acid generators include those of the following FormulaIV:

wherein T, T′, T″, A, B, C, J, n, n′, n″ and Z are as defined forFormula (II); and R is a group comprising an acid-labile moiety.

Still further preferred acid generators include those of the followingFormula V:

wherein T, T′, T″, A, B, C, J, n, n′, n″ and Z are as defined forFormula (IV), D and D′ are the same or different and are each hydrogenor a non-hydrogen substituent, and optionally taken together may form aring, and R₂ is H or a group comprising an acid-labile moiety.

Preferred acid generators and photoresists of the invention areparticularly useful for short-wavelength imaging, such as 193 nm and EUVimaging.

In preferred aspects, photoresist compositions are provided comprising(i) a polymer; (ii) an acid generator as disclosed herein.

In preferred aspects, the acid generators are acid-labile and react inthe presence of acid during lithographic processing (exposure,post-exposure bake) of a photoresist coating layer containing the acidgenerator.

Preferred photoresists of the invention may comprise animaging-effective amount of one, two or more acid generator compounds asdisclosed herein and a suitable polymer component.

Methods are also provided for forming relief images of photoresistcompositions of the invention (including patterned lines with sub sub-50nm or sub-20 nm dimensions). Substrates such as a microelectronic waferalso are provided having coated thereon a photoresist composition of theinvention.

Other aspects of the invention are disclosed infra.

DETAILED DESCRIPTION

As referred to herein, acid generators can produce an acid when exposedto activating radiation, such as EUV radiation, e-beam radiation orother radiation sources such as 193 nm wavelength radiation. Acidgenerators as referred to herein also may be referred to as photoacidgenerator compounds.

Acid Generators

As discussed above, in preferred aspects, ionic photoacid generatorsthat comprise at least one acetate moiety are provided, includingcompounds of Formula I-V above.

As used herein, the term “diester moiety” refers to a moiety having twoester moieties linked by a linking group:—C(═O)O-L-C(═O)OR,in which L is a linking group. Preferred diesters can be represented bya structure of the formula:—Y—C(═O)O(CX′X″)_(n)C(═O)ORin which Y is a linker comprising one or more carbon atoms (such as a—CH₂— group), provided that Y is unsubstituted (i.e., has nonon-hydrogen substituents);

n is a positive integer

each X′ and X″ is independently a hydrogen or non-hydrogen substituent;and R is a non-hydrogen substituent such as optionally substitutedalkyl, optionally substituted heteroalkyl, optionally substitutedalicyclic, optionally substituted heteroalicyclic, optionallysubstituted carbocyclic aryl or optionally substituted heteroaromatic.

Additional ionic photoacid generators that comprise at least one acetatemoiety including compounds represented by the following Formula VI:

wherein

D, D′, T, T′, T″, J, n, n′, n″, and Z are as defined for Formula (V), R₂is hydrogen or a non-hydrogen substituent, and B and C are each the sameor different optionally substituted phenyl group.

Additional ionic photoacid generators that comprise at least one acetatemoiety including compounds represented by the following Formula VII:

wherein

T, T′, T″, J, A, B, C, n, n′, n″, and Z are as defined for Formula (V);R₂ is hydrogen or a non-hydrogen substituent; and Q is a C₁-C₈ alkylenegroup which may be fully or partially saturated, any of the carbongroups may be substituted with a carbonyl, oxygen, nitrogen, sulfur orany combination of carbonyl, oxygen, nitrogen, sulfur; a C₁ to C₃₀aliphatic hydrocarbon group, a C₆ to C₃₀ aromatic hydrocarbon group, aC₁ to C₃₀ cyclic hydrocarbon group, a C₁ to C₃₀ polycyclic hydrocarbongroup, a C₅ to C₃₀ heteroaromatic group.

Still further ionic photoacid generators that comprise at least oneacetate moiety include compounds of the following Formula VIII:

wherein

T, T′, T″, A, B, C, J, n, n′, n″, and R are as defined for Formula (II);W, W′, W″, and W′″ may be taken from hydrogen, deuterium, fluorine,cyano, or trifluoromethyl, or any combination of hydrogen, deuterium,fluorine, cyano, or trifluoromethyl; and R″ is a non-hydrogensubstituent.

Also preferred are acid generator of the above formulae (includingForumlae (I), (II), (IIa), (III), (IIIA), (IV), (V), (VI) and (VII)wherein Z⁻ comprises a structure of Formula (IX):

wherein:

-   -   Y is a sulfonate, carboxylate, sulfate, sulfamate, or the anion        of a sulfonamide or sulfonimide;    -   R′″ is a hydrogen or non-hydrogen substituent; and    -   W and W′ are independently chosen from hydrogen, fluorine,        cyano, optionally substituted alkyl and optionally substituted        aryl, wherein two or more of W, W′ and R′″ together optionally        form a ring;    -   provided that when W and W′ are each independently fluorine or        perfluoroalkyl, Y is chosen from carboxylate, sulfate,        sulfamate, or the anion of a sulfonamide or sulfonimide.

In the above Formulae (II)-(VIII), J suitably can be a single bond,optionally substituted alkylene group, C═O, O, S, SO, SO₂, NH, or NR(where R is a non-hydrogen substituent such as optionally substitutedalkyl). J linker groups also may comprise various hetero groups andmoieties such as ether, ester, amide, carbonate, sulfonate, sulfone, orsulfonamide, e.g. CH₂(C═O)—O—, CH₂(C═O)—OCH₂CH₂—, CH₂(C═O)—OCH₂CH₂O—,CH₂(C═O)—OCH₂—, CH₂(C═O)—OCH₂O—, —O—, —S—, —O—C(═O)—, —C(═O)—O—,—O—C(═O)—O—, —OCH₂—(C═O)O— or —OCH₂C(═O)—.

In certain embodiments of Formulae (I)-(VIII), the counter anion Z is acarboxylate or sulfamate anion. In certain embodiments, the counteranion Z contains a polymerizable moiety.

Specifically preferred cations of ionic acid generators acid generatorinclude the following:

Preferred anion components (Z in the above formulae) of ionic acidgenerators of the invention include those where wherein the anion chargeresides with a sulfonate group, a carboxylate group, a carbon atom,nitrogen atom or boron atom. Exemplary Z groups may comprises optionallysubstituted alkylsulfonate and optionally substituted carbocyclicarylsulfonate.

Preferred anion components (Z in the above formulae) of ionic acidgenerators of the invention include those of the following formula:A-(L¹)-(C(R⁴)₂)_(m1)—(C(R⁵)₂)_(n2)—SO₃ ⁻

wherein A is a substituted or unsubstituted, monocyclic, polycyclic, orfused polycyclic C₃ or greater aliphatic or aromatic groups optionallycomprising O, S, N, F, or a combination comprising at least one of theforegoing, or a C₃ or greater aliphatic or cycloaliphatic groupcontaining a polymerizable double or triple bond. Preferred groups Ainclude polycyclic aliphatic groups such as adamantyl groups,norbornenyl groups, and cycloalkylenyl groups substituted with hydroxy,ester, lactone, acetyl, ketyl, or combinations of these groups.

R⁴ is H, a single bond, or a substituted or unsubstituted C₁₋₃₀ alkylgroup, wherein when R⁴ is a single bond, R⁴ is covalently bonded to acarbon atom of A. Each R⁵ is independently H, F, or C₁₋₄ fluoroalkyl,wherein at least one R⁵ is not hydrogen. L¹ is a linking groupcomprising an —O—, —S—, —C(═O)—, carbonate, carboxylate, sulfonate,sulfate, or a sulfonamide group. Further, m1 is an integer of greaterthan or equal to 0, preferably 0 to 10, and also preferably 1 to 5, andn2 is an integer of greater than or equal to 0, preferably 1 to 10, andalso preferably 1 to 5.

Exemplary anion components (Z in the above formulae) of ionic acidgenerators of the invention include the following:

As mentioned above, acid generators of the invention may be covalentlybound to a larger polymer. In certain embodiments, a resin or matrixpolymer contains an ionic photoacid generator that comprises at leastone acetate moiety, wherein the ionic photoacid generator is bound tothe resin or matrix polymer by the cation or anion.

For an ionic acid generator, suitably either cation or anion componentsare covalently linked to a larger polymer, or both cation and anioncomponents are covalently bound to the polymer.

For instance, the anion component may comprise a polymerizable group(such as acrylate, methacrylate, vinyl ether) which can be reacted witha pre-formed polymer, or other monomers, to provide the polymer-boundacid generator. Exemplary polymerizable anion components include thefollowing structures:

As discussed above, the present acid generator may be acid-labile andundergo a bond-breaking reaction during lithographic processing of aphotoresist comprising the acid generator. As discussed above, an acidgenerator acetate moiety itself may be photoacid-labile and react underlithographic processing of a photoresist comprising the acid generator.An acid generator also may comprise other substituents that arephotoacid-labile. As referred to herein, acid-labile moieties or groups(including acid-labile esters and acetals) undergo reaction in thepresence of generated acid (from an acid generator compound in a resist)during typical lithographic processing, including any post-radiationexposure thermal exposure. Acid-labile groups as referred to herein alsomay be referred to as photoacid-labile groups.

Suitable acid-labile groups of acid generators may be a variety ofmoieties, including acid-labile esters and acetals such as optionallysubstituted ethylcyclopentyl ester, methyladamantyl ester, ethyladamantyl ester, t-butylester, phenyl ester, naphthyl ester and others.Suitable acid-labile groups of acid generators also may include groupsof the following formula (IX) and ester photoacid-labile groups of thefollowing formula X:—O(CXY)_(n)R³  (IX)

wherein in Formula (IX), X and Y are independently hydrogen or anon-hydrogen substituent such as halogen (F, Cl, Br, I), C₁₋₁₀alkyl,C₁₋₁₀alkoxy; R³ is a non-hydrogen substituent that provides anacid-labile moiety such as a carbamate, an acid-labile ester or acetalgroup; and n is a positive integer such as any of 1 through 20, moretypically n is any of 1-10 or 1-4. Exemplary preferred R³ groups includet-butyl, or more preferably a further ester linkage such as where R³ is—(CH₂)n(C═O)O-ALG, where n is an integer of from 1 to 12, preferably nis 1, 2, 3 or 4, and ALG is a group (e.g. that provides a quaternarycarbon linked to the ester) that results in an acid labile moiety, suchas t-butyl or a ring system with linking quaternary carbon such as1-ethylcyclopentyl or methyladamantyl;—(C═O)OR³  (X)

wherein in Formula (X), R³ is a non-hydrogen substituent that providesan acid-labile moiety such as a carbamate, an acid-labile ester oracetal group. For instance, exemplary preferred R³ groups includet-butyl, or more preferably a further ester linkage such as where R³ is—(CH₂)n(C═O)O-ALG, where n is an integer of from 1 to 12, preferably nis 1, 2, 3 or 4, and ALG is a group (e.g. that provides a quaternarycarbon linked to the ester) that results in an acid labile moiety, suchas t-butyl or a ring system with linking quaternary carbon such as1-ethylcyclopentyl or methyladamantyl.

In certain aspects, an acid generator of the invention will not containany acid-labile groups other than an acetate or diester moiety.

In the above formulae, suitable non-hydrogen substituents may be halo(F, Cl, Br or I); deuterium, cyano, nitro, hydroxy, optionallysubstituted C₁₋₂₀ alkyl, optionally substituted C₁₋₂₀ alkoxy, such asoptionally substituted alkyl (e.g. optionally substituted C₁₋₁₀ alkyl),optionally substituted alkenyl or alkynyl preferably having 2 to about20 carbon atoms such as such as allyl; optionally substituted ketonespreferably having 1 to about 20 carbon atoms; optionally substitutedalkylthio preferably having 1 to about 20 carbon atoms; optionallysubstituted alkylsulfinyl preferably 1 to about 20 carbon atoms;optionally substituted alkylsulfonyl preferably having 1 to about 20carbon atoms; optionally substituted carboxy preferably have 1 to about20 carbon atoms (which includes groups such as —COOR′ where R′ is H orC₁₋₈alkyl, including esters that are substantially non-reactive withphotoacid); optionally substituted alkaryl such as optionallysubstituted benzyl, optionally substituted C₆₋₁₄ carbocyclic aryl suchas optionally substituted phenyl, naphthyl, acenaphthyl, or optionallysubstituted heteroalicyclic or heteroaromatic group having from 5 to 14atoms, including 1-4 heteroatoms selected from O, S, and N, in the ringsystem, such as pyridyl, furanyl, pyrrole, thiophene, furan, imidazole,pyrazole, oxazole, isoxazole, thiazole, isothiazole, triazole, furanzan,oxadiazole, thiadiazole, dithiazole, terazole, pyran, thiopyran,diazine, oxazine, thiazine, dioxine, dithine, and triazine andpolyaromatic groups containing one or more of such moieties.

Preferred acid generators of the invention may comprise one or moreelectron withdrawing moieties, which suitably may be e.g. halogen suchas Cl, Br or F with F being preferred, C₁₋₂₀haloalkyl with fluoroalkylbeing preferred including perfluoralkyl; cyano; nitro;C₁₋₂₀alkylsulfonyl, —COOH; and >C═O. For ionic acid generators, one ormore electron withdrawing substituents may be on either cation or anioncomponents.

As discussed, various moieties of acid generators and other materialsmay be optionally substituted. A “substituted” substituent may besubstituted at one or more available positions, typically 1, 2, or 3positions by one or more suitable groups such as e.g. halogen(particularly F, Cl or Br); cyano; nitro; C₁₋₈ alkyl; C₁₋₈ alkoxy; C₁₋₈alkylthio; C₁₋₈ alkylsulfonyl; C₂₋₈ alkenyl; C₂₋₈ alkynyl; hydroxyl;nitro; alkanoyl such as a C₁₋₆ alkanoyl e.g. acyl, haloalkylparticularly C₁₋₈ haloalkyl such as CF₃; —CONHR, —CONRR′ where R and R′are optionally substituted C₁₋₈ alkyl; —COOH, COC, >C═O; and the like.

Acid generators of the invention can be readily prepared. Exemplarypreferred syntheses are set forth in the examples which follow.

Photoresist Compositions

As discussed above, acid generators as disclosed herein are useful asthe radiation sensitive component in photoresist compositions, includingboth positive-acting and negative-acting chemically amplified resistcompositions. The acid generators of this invention may be used as partof: a cation or anion bound matrix resin or polymer; or a discreteblended acid generator in the presence of a matrix resin or polymer thatmay or may not contain an cation or anion bound acid generator.

The photoresists of the invention typically comprise a polymer and oneor more acid generators as disclosed herein. Preferably the polymer hasfunctional groups that impart alkaline aqueous developability to theresist composition. For example, preferred are polymers that comprisepolar functional groups such as hydroxyl or carboxylate, or acid-labilegroups that can liberate such polar moieties upon lithographicprocessing. Preferably the polymer is used in a resist composition in anamount sufficient to render the resist developable with an aqueousalkaline solution.

Acid generators are also suitably used with polymers that compriserepeat units containing aromatic groups, such as optionally substitutedphenyl including phenol, optionally substituted naphthyl, and optionallysubstituted anthracene. Optionally substituted phenyl (including phenol)containing polymers are particularly suitable for many resist systems,including those imaged with EUV and e-beam radiation. Forpositive-acting resists, the polymer also preferably contains one ormore repeat units that comprise acid-labile groups. For example, in thecase of polymers containing optionally substituted phenyl or otheraromatic groups, a polymer may comprise repeat units that contain one ormore acid-labile moieties such as a polymer that is formed bypolymerization of monomers of an acrylate or methacrylate compound withacid-labile ester (e.g. t-butyl acrylate or t-butyl methacrylate). Suchmonomers may be copolymerized with one or more other monomers thatcomprise aromatic group(s) such as optionally phenyl, e.g. a styrene orvinyl phenol monomer.

Preferred monomers used for the formation of such polymers include: anacid-deprotectable monomer having the following formula (XI), alactone-containing monomer of the following formula (XII), abase-soluble monomer of the following formula (XIII) for adjustingdissolution rate in alkaline developer, and a photoacid-generatingmonomer of the following formula (XIV), or a combination comprising atleast one of the foregoing monomers:

wherein each R^(a) is independently H, F, —CN, C₁₋₁₀ alkyl, or C₁₋₁₀fluoroalkyl. In the acid-deprotectable monomer of formula (XI), R^(b) isindependently C₁₋₂₀ alkyl, C₃₋₂₀ cycloalkyl, C₆₋₂₀ aryl, or C₇₋₂₀aralkyl, and each R^(b) is separate or at least one R^(b) is bonded toan adjacent R^(b) to form a cyclic structure. In lactone-containingmonomer of formula (XII), L is a monocyclic, polycyclic, or fusedpolycyclic C₄₋₂₀ lactone-containing group. In the base solubilizingmonomer of formula (XIII), W is a halogenated or non-halogenated,aromatic or non-aromatic C₂₋₅₀ hydroxyl-containing organic group havinga pKa of less than or equal to 12. In the photoacid generating monomerof formula (XIV), Q is ester-containing or non-ester containing andfluorinated or non-fluorinated and is C₁₋₂₀ alkyl, C₃₋₂₀ cycloalkyl,C₆₋₂₀ aryl, or C₇₋₂₀ aralkyl group, A is ester-containing ornon-ester-containing and fluorinated or non-fluorinated, and is C₁₋₂₀alkyl, C₃₋₂₀ cycloalkyl, C₆₋₂₀ aryl, or C₇₋₂₀ aralkyl, Z⁻ is an anionicmoiety comprising carboxylate, sulfonate, an anion of a sulfonamide, oran anion of a sulfonimide, and G⁺ is a sulfonium or iodonium cation.

Exemplary acid-deprotectable monomers include but are not limited to:

or a combination comprising at least one of the foregoing, wherein R^(a)is H, F, —CN, C₁₋₆ alkyl, or C₁₋₆ fluoroalkyl.

Suitable lactone monomers may be of the following formula (XV):

wherein R^(a) is H, F, —CN, C₁₋₆ alkyl, or C₁₋₆ fluoroalkyl, R is aC₁₋₁₀ alkyl, cycloalkyl, or heterocycloalkyl, and w is an integer of 0to 5. In formula (XV), R is attached directly to the lactone ring orcommonly attached to the lactone ring and/or one or more R groups, andthe ester moiety is attached to the lactone ring directly, or indirectlythrough R.

Exemplary lactone-containing monomers include:

or a combination comprising at least one of the foregoing monomers,wherein R^(a) is H, F, —CN, C₁₋₁₀ alkyl, or C₁₋₁₀ fluoroalkyl.

Suitable base-soluble monomers may be of the following formula (XVI):

wherein each R^(a) is independently H, F, —CN, C₁₋₁₀ alkyl, or C₁₋₁₀fluoroalkyl, A is a hydroxyl-containing or non-hydroxyl containing,ester-containing or non ester-containing, fluorinated or non-fluorinatedC₁₋₂₀ alkylene, C₃₋₂₀ cycloalkylene, C₆₋₂₀ arylene, or C₇₋₂₀ aralkylene,and x is an integer of from 0 to 4, wherein when x is 0, A is ahydroxyl-containing C₆₋₂₀ arylene.

Exemplary base soluble monomers include those having the followingstructures:

or a combination comprising at least one of the foregoing, wherein R^(a)is H, F, —CN, C₁₋₆alkyl, or C₁₋₆ fluoroalkyl.

Preferred photoacid generating monomer include those of the formulae(XVII) or (XVIII):

wherein each R^(a) is independently H, F, —CN, C₁₋₆alkyl, or C₁₋₆fluoroalkyl, A is a fluorine-substituted C₁₋₃₀ alkylene group, afluorine-substituted C₃₋₃₀ cycloalkylene group, a fluorine-substitutedC₆₋₃₀ arylene group, or a fluorine-substituted C₇₋₃₀ alkylene-arylenegroup, and G⁺ is a sulfonium or iodonium cation.

Preferably, in formulas (XVII) and (XVIII), A is a—[(C(R¹)₂)_(x)C(═O)O]_(b)—C((R²)₂)_(y)(CF₂)_(z)— group, or an o-, m- orp-substituted —C₆F₄— group, where each R¹ and R² are each independentlyH, F, —CN, C₁₋₆ fluoroalkyl, or C₁₋₆ alkyl, b is 0 or 1, x is an integerof 1 to 10, y and z are independently integers of from 0 to 10, and thesum of y+z is at least 1.

Exemplary preferred photoacid generating monomers include:

or a combination comprising at least one of the foregoing, where eachR^(a) is independently H, F, —CN, C₁₋₆ alkyl, or C₁₋₆ fluoroalkyl, k issuitably an integer of from 0 to 5; and G⁺ is a sulfonium or iodoniumcation.

Preferred photoacid-generating monomers may include sulfonium oriodonium cation. Preferably, in the formulae above, G⁺ is of the formula(XIX):

wherein X is S or I, each R⁰ is halogenated or non-halogenated and isindependently C₁₋₃₀ alkyl group; a polycyclic or monocyclic C₃₋₃₀cycloalkyl group; a polycyclic or monocyclic C₄₋₃₀ aryl group; or acombination comprising at least one of the foregoing, wherein when X isS, one of the R⁰ groups is optionally attached to one adjacent R⁰ groupby a single bond, and a is 2 or 3, wherein when X is I, a is 2, or whenX is S, a is 3.

Exemplary acid generating monomers include those having the formulas:

Specifically suitable polymers that have acid-labile deblocking groupsfor use in a positive-acting chemically-amplified photoresist of theinvention have been disclosed in US Patent Application 20130209934,European Patent Application 0829766A2 (polymers with acetal and ketalpolymers) and European Patent Application EP0783136A2 (terpolymers andother copolymers including units of 1) styrene; 2) hydroxystyrene; and3) acid-labile groups, particularly alkyl acrylate acid-labile groups.

Polymers for use in photoresists of the invention may suitably varywidely in molecular weight and polydisperity. Suitable polymers includethose that have an M_(w) of from about 1,000 to about 50,000, moretypically about 2,000 to about 30,000 with a molecular weightdistribution of about 3 or less, more typically a molecular weightdistribution of about 2 or less.

Preferred negative-acting compositions of the invention comprise amixture of materials that will cure, crosslink or harden upon exposureto acid, and one, two, or more photoacid generators as disclosed herein.Preferred negative acting compositions comprise a polymer binder such asa phenolic or non-aromatic polymer, a crosslinker component and aphotoactive component of the invention. Such compositions and the usethereof have been disclosed in European Patent Applications 0164248 andU.S. Pat. No. 5,128,232 to Thackeray et al. Preferred phenolic polymersfor use as the polymer binder component include novolaks andpoly(vinylphenol)s such as those discussed above. Preferred crosslinkersinclude amine-based materials, including melamine, glycolurils,benzoguanamine-based materials and urea-based materials.Melamine-formaldehyde polymers are often particularly suitable. Suchcrosslinkers are commercially available, e.g. the melamine polymers,glycoluril polymers, urea-based polymer and benzoguanamine polymers,such as those sold by Cytec under tradenames Cymel 301, 303, 1170, 1171,1172, 1123 and 1125 and Beetle 60, 65 and 80.

Photoresists of the invention also may contain other materials. Forexample, other optional additives include actinic and contrast dyes,anti-striation agents, plasticizers, speed enhancers and sensitizers.Such optional additives typically will be present in minor concentrationin a photoresist composition.

Alternatively, or in addition, other additives may include quenchersthat are non-photo-destroyable bases, such as, for example, those basedon hydroxides, carboxylates, amines, imines, and amides. Preferably,such quenchers include C₁₋₃₀ organic amines, imines, or amides, or maybe a C₁₋₃₀ quaternary ammonium salt of a strong base (e.g., a hydroxideor alkoxide) or a weak base (e.g., a carboxylate). Exemplary quenchersinclude amines such as tripropylamine, dodecylamine,tris(2-hydroxypropyl)amine, oltetrakis(2-hydroxypropyl)ethylenediamine;aryl amines such as diphenylamine, triphenylamine, aminophenol, and2-(4-aminophenyl)-2-(4-hydroxyphenyl)propane, Troger's base, a hinderedamine such as diazabicycloundecene (DBU) or diazabicyclononene (DBN), orionic quenchers including quaternary alkyl ammonium salts such astetrabutylammonium hydroxide (TBAH) or tetrabutylammonium lactate.

Surfactants include fluorinated and non-fluorinated surfactants, and arepreferably non-ionic. Exemplary fluorinated non-ionic surfactantsinclude perfluoro C₄ surfactants such as FC-4430 and FC-4432surfactants, available from 3M Corporation; and fluorodiols such asPOLYFOX PF-636, PF-6320, PF-656, and PF-6520 fluorosurfactants fromOmnova.

The photoresist further includes a solvent generally suitable fordissolving, dispensing, and coating the components used in aphotoresists. Exemplary solvents include anisole, alcohols includingethyl lactate, 1-methoxy-2-propanol, and 1-ethoxy-2 propanol, estersincluding n-butylacetate, 1-methoxy-2-propyl acetate,methoxyethoxypropionate, ethoxyethoxypropionate, ketones includingcyclohexanone and 2-heptanone, and a combination comprising at least oneof the foregoing solvents.

Such photoresists may include the polymer in an amount of 50 to 99 wt %,specifically 55 to 95 wt %, more specifically 60 to 90 wt %, and stillmore specifically 65 to 90 based on the total weight of solids. Aphoto-destroyable base may be present in the photoresist in an amount of0.01 to 5 wt %, specifically 0.1 to 4 wt %, and still more specifically0.2 to 3 wt %, based on the total weight of solids. Photo-destroyablebases include photo-decomposable cations, and preferably those alsouseful for preparing PAGs, paired with an anion of a weak (pKa >2) acidsuch as, for example, a C₁₋₂₀ carboxylic acid. Exemplary such carboxylicacids include formic acid, acetic acid, propionic acid, tartaric acid,succinic acid, cyclohexylcarboxylic acid, benzoic acid, salicylic acid,and other such carboxylic acids. A surfactant may be included in anamount of 0.01 to 5 wt %, specifically 0.1 to 4 wt %, and still morespecifically 0.2 to 3 wt %, based on the total weight of solids. Aquencher may be included in relatively small amounts of for example,from 0.03 to 5 wt % based on the total weight of solids. Other additivesmay be included in amounts of less than or equal to 50 wt %,specifically less than or equal to 35%, or more specifically less thanor equal to 25%, based on the total weight of solids. The total solidscontent for the photoresist composition may be 0.5 to 50 wt %,specifically 1 to 45 wt %, more specifically 2 to 40 wt %, and stillmore specifically 5 to 30 wt %, based on the total weight of solids andsolvent. The acid generators should be present in an amount sufficientto enable generation of a latent image in a coating layer of the resist.More specifically, the photoacid generator(s) will suitably be presentin an amount of from about 1 to 50 weight percent of total solids of aresist. It will be understood that the solids includes polymer,quencher, surfactant, and any optional additives, exclusive of solvent.

A coated substrate may be formed from the photoresist containing acidgenerators which should be present in an amount sufficient to enablegeneration of a latent image in a coating layer of the resist and acidgenerators. Such a coated substrate includes: (a) a substrate having oneor more layers to be patterned on a surface thereof; and (b) a layer ofthe photoresist composition including the acid generator over the one ormore layers to be patterned. For EUV or e-beam imaging, photoresists maysuitably have relatively higher content of acid generator compounds,e.g. where the one or more acid generators comprise 5 to 10 to about 65weight percent of total solids of the resist. Typically, lesser amountsof the photoactive component will be suitable for chemically amplifiedresists.

The photoresists of the invention are generally prepared following knownprocedures with the exception that one or more acid generator compoundsof the invention are substituted for prior photoactive compounds used inthe formulation of such photoresists. The photoresists of the inventioncan be used in accordance with known procedures.

Substrates may be any dimension and shape, and are preferably thoseuseful for photolithography, such as silicon, silicon dioxide,silicon-on-insulator (SOI), strained silicon, gallium arsenide, coatedsubstrates including those coated with silicon nitride, siliconoxynitride, titanium nitride, tantalum nitride, ultrathin gate oxidessuch as hafnium oxide, metal or metal coated substrates including thosecoated with titanium, tantalum, copper, aluminum, tungsten, alloysthereof, and combinations thereof. Preferably, the surfaces ofsubstrates herein include critical dimension layers to be patternedincluding, for example, one or more gate-level layers or other criticaldimension layer on the substrates for semiconductor manufacture. Suchsubstrates may preferably include silicon, SOI, strained silicon, andother such substrate materials, formed as circular wafers havingdimensions such as, for example, 20 cm, 30 cm, or larger in diameter, orother dimensions useful for wafer fabrication production.

Further, a method of forming an electronic device includes (a) applyinga layer of a photoresist composition including on a surface of thesubstrate; (b) patternwise exposing the photoresist composition layer toactivating radiation; and (c) developing the exposed photoresistcomposition layer to provide a resist relief image.

Applying may be accomplished by any suitable method, including spincoating, spray coating, dip coating, doctor blading, or the like.Applying the layer of photoresist is preferably accomplished byspin-coating the photoresist in solvent using a coating track, in whichthe photoresist is dispensed on a spinning wafer. During dispense, thewafer may be spun at a speed of up to 4,000 rpm, preferably from about500 to 3,000 rpm, and more preferably 1,000 to 2,500 rpm. The coatedwafer is spun to remove solvent, and baked on a hot plate to removeresidual solvent and free volume from the film to make it uniformlydense.

Patternwise exposure is then carried out using an exposure tool such asa stepper, in which the film is irradiated through a pattern mask andthereby is exposed pattern-wise. The method preferably uses advancedexposure tools generating activating radiation at wavelengths capable ofhigh resolution including extreme-ultraviolet (EUV) or e-beam radiation.It will be appreciated that exposure using the activating radiationdecomposes the PAG in the exposed areas and generates acid anddecomposition by-products, and that the acid then effects a chemicalchange in the polymer (deblocking the acid sensitive group to generate abase-soluble group, or alternatively, catalyzing a cross-linkingreaction in the exposed areas). The resolution of such exposure toolsmay be less than 30 nm.

Developing the exposed photoresist layer is then accomplished bytreating the exposed layer to a suitable developer capable ofselectively removing the exposed portions of the film (where thephotoresist is positive tone) or removing the unexposed portions of thefilm (where the photoresist is crosslinkable in the exposed regions,i.e., negative tone). Preferably, the photoresist is positive tone basedon a polymer having acid sensitive (deprotectable) groups, and thedeveloper is preferably a metal-ion free tetraalkylammonium hydroxidesolution, such as, for example, aqueous 0.26 N tetramethylammoniumhydroxide. A pattern forms by developing.

Additionally, for positive resists, unexposed regions can be selectivelyremoved by treatment with a suitable nonpolar solvent for negative tonedevelopment. See U.S. 2011/0294069 for suitable procedures for negativetone development of positive photoresists. Typical nonpolar solvents fornegative tone development are organic developers, such as a solventchosen from ketones, esters, hydrocarbons, and mixtures thereof, e.g.acetone, 2-hexanone, methyl acetate, butyl acetate, and tetrahydrofuran.

The photoresist may, when used in one or more such a pattern-formingprocesses, be used to fabricate electronic and optoelectronic devicessuch as memory devices, processor chips (CPU's), graphics chips, andother such devices.

Example 1

5-(3-(Carboxymethyl)-4-methoxyphenyl)-dibenzothiophenium iodide

Eaton's Reagent (phosphorus pentoxide solution in methanesulfonic acid)(400 mL) was added to a solution of 2-methoxyphenylacetic acid (140 g,0.843 mol) and dibenzothiophene oxide (160 g, 0.800 mol) indichloromethane (400 mL), stirred at 25° C. for 18 h, cooled to 0° C.and carefully quenched with water (1 L). The aqueous mixture was washedwith MTBE (3×500 mL) and the aqueous phase poured onto aqueous sodiumiodide (300 g in 3 L) followed by vigorously stirred for 1 h. Theprecipitate was filtered, washed with water (3×1 L), acetone (1 L) andMTBE (2×500 mL) to afford the title compound as a white solid (360 g,94%). ¹H NMR (500 MHz, (CD₃)₂SO) δ: 12.30 (brs, COOH), 8.52 (d, J=7.5Hz, 2H), 8.31 (d, J=8.5 Hz, 2H), 7.95 (t, J=7 Hz, 2H), 7.75 (t, J=8 Hz,2 h), 7.70 (dd, J=9, 2 Hz, 1H), 7.31 (d, J=2 Hz, 1H), 7.23 (d, J=8.5 Hz,1H), 3.82 (s, 3H), 3.46 (s, 2H).

Example 2

5-(4-methoxy-3-(2-(2-((2-methyladamantan-2-yl)oxy)-2-oxoethoxy)-2-oxoethyl)phenyl)-dibenzothiopheniumchloride

5-(3-(carboxymethyl)-4-methoxyphenyl)-dibenzothiophenium iodide (15.0 g,31.5 mmol) was dissolved in DMF (100 mL) and degassed with nitrogen for30 min, then 2-methyladamantan-2-yl 2-chloroacetate (7.49 g, 31.0 mmol)and cesium carbonate (14.4 g, 44.1 mmol) were added sequentially and themixture stirred at 25° C. for 6 h. The solution was diluted with water(200 mL), extracted with DCM (2×150 mL), the combined organic layerswashed with water (5×150 mL) and concentrated to a viscous oil which waspoured onto MTBE (1 L) and vigorously stirred for 1 h. The precipitatewas filtered, washed with MTBE (2×250 mL) and dried to afford the titlecompound (18.2 g, 99%) as a white solid. ¹H NMR (300 MHz, (CD₃)₂SO) δ:8.51 (d, J=8.1 Hz, 2H), 8.29 (d, J=8.1 Hz, 2H), 7.95 (t, J=7.5 Hz, 2H),7.70-7.81 (m, 3H), 7.32 (d, J=2.1 Hz, 1H), 7.25 (dd, J=7.5, 2.1 Hz, 1H),4.56 (s, 2H), 3.82 (s, 3H), 3.65 (s, 2H), 2.10-2.19 (m, 2H), 1.61-1.95(m, 11H), 1.52 (s, 3H), 1.39-1.50 (m, 2H).

Example 3

5-(3-(2-(carboxymethoxy)-2-oxoethyl)-4-methoxyphenyl)-dibenzothiopheniumchloride

Triflic acid (trifluoromethansulfonic acid) (0.5 mL) was added to asolution of5-(4-methoxy-3-(2-(2-((2-methyladamantan-2-yl)oxy)-2-oxoethoxy)-2-oxoethyl)phenyl)-dibenzothiopheniumchloride (3.00 g, 5.07 mmol) in DCM (50 mL) and stirred at 25° C. for 48h. The precipitate was filtered, washed with MTBE:Acetone (50 mL) andMTBE (2×100 mL) to afford the title compound (2.05 g, 91%) as a whitesolid. ¹H NMR (300 MHz, (CD₃)₂SO) δ: 12.5 (brs, COOH), 8.52 (d, J=7.8Hz, 2H), 8.29 (d, J=8.1 Hz, 2H), 7.95 (t, J=7.5 Hz, 2H), 7.67-7.79 (m,3H), 7.38 (vis s, 1H), 7.22 (d, J=8.1 Hz, 1H), 4.51 (s, 2H), 3.81 (s,3H), 3.66 (s, 2H).

Example 4

5-(4-methoxy-3-(2-(2-((2-methyladamantan-2-yl)oxy)-2-oxoethoxy)-2-oxoethyl)phenyl)-dibenzothiophenium1,1,2,2-tetrafluoro-4-((3-hydroxyadamantane-1-carbonyl)oxy)butane-1-sulfonate

5-(4-methoxy-3-(2-(2-((2-methyladamantan-2-yl)oxy)-2-oxoethoxy)-2-oxoethyl)phenyl)-dibenzothiopheniumchloride (6.75 g, 11.4 mmol) and sodium3-hydroxyadamantane-acetoxy-1,1,2,2-tetrafluorobutane-1-sulfonate (11.4mmol, 4.87 g) were dissolved in DCM (150 mL) and water (150 mL) andstirred at 25° C. overnight. The layers were separated, the aqueousphase extracted with dichloromethane (70 mL), the combined organiclayers washed with water (10×150 mL) and concentrated under reducedpressure to afford the title compound (8.86 g, 81%) as a white solid. ¹HNMR (500 MHz, (CD₃)₂CO) δ: 8.53 (d, J=8 Hz, 2H), 8.36 (d, J=8 Hz, 2H),8.02 (t, J=7.5 Hz, 2H), 7.85 (dd, J=9, 2 Hz, 1H), 7.82 (t, J=7.5 Hz,2H), 7.63 (d, J=2 Hz, 1H), 7.31 (d, J=9 Hz, 1H), 4.58 (s, 2H), 4.34 (t,J=6.5 Hz, 2H), 3.96 (s, 3H), 3.70 (s, 2H), 3.58 (s, 1OH), 2.71 (tt,J=18.5, 7 Hz, 2H), 2.14-2.28 (m, 4H), 1.87-2.40 (m, 5H), 1.50-1.83 (m,23H).

Example 5

(4-(2-methoxy-2-oxoethyl)naphthalen-1-yl)diphenylsulfonium iodide

Triflic anhydride (16.6 mL, 0.099 mmol) was added dropwise to a solutionof diphenylsulfoxide (10.0 g, 49.4 mmol) and methyl2-(naphthalen-1-yl)acetate (10.9 g, 54.5 mmol) in DCM (100 mL) at −78°C. and stirred for 3 h. The reaction was quenched by the slow additionof water (50 mL) and slowly warmed to r.t. The layers were separated andthe organic layer washed with 2M aqueous sodium iodide (10×100 mL), andwater (3×100 mL), then concentrated to a viscous oil which wasprecipitated from MTBE (600 mL) to afford the title compound (18.7 g,74%) as a light brown hydroscopic solid. ¹H NMR (500 MHz, (CD₃)₂CO) δ:8.48-8.51 (m, 1H), 8.30-8.33 (m, 1H), 8.03-8.10 (m, 3H), 7.75-7.99 (m,8H), 7.72 (d, J=8 Hz, 1H). 4.39 (s, 2H), 3.68 (s, 3H).

Example 6

10-(4-methoxy-3-(2-methoxy-2-oxoethyl)phenyl)-9-oxo-9,10-dihydrothioxanthyliumtriflate

Triflic acid (7.3 mL, 43.4 mmol) was added dropwise to a solution ofthioxanthone oxide (5.00 g, 21.7 mmol) and methyl2-(2-methoxyphenyl)acetate (4.31 g, 23.9 mmol) in DCM (60 mL) at −78° C.and slowly warmed to 25° C. overnight. The reaction mixture was quenchedwith water (100 mL), the layers separated, and the aqueous phase washedwith water (4×100 mL) and concentrated to a crude solid. The crude solidwas dissolved in minimal acetone, precipitated into MTBE (1 L), andfiltered to afford the title compound (10.0 g, 85%) as a white solid. ¹HNMR (500 MHz, (CD₃)₂CO) δ: 8.66-8.69 (m, 2H), 8.19-8.22 (m, 3H),8.10-8.13 (m, 4H), 7.91 (d, J=2.5 Hz, 1H), 7.37 (d, J=9 Hz, 1H), 3.96(s, 3H), 3.61 (s, 2H), 3.57 (s, 3H).

Example 7

5-(4-methoxy-3-(2-oxo-2-(2-oxo-2-(2-oxo-2-((2-phenylpropan-2-yl)oxy)ethoxy)ethoxy)ethyl)phenyl)-dibenzothiopheniumchloride

5-(3-(2-(carboxymethoxy)-2-oxoethyl)-4-methoxyphenyl)dibenzothiopheniumchloride (25 g, 59.2 mmol), 2-phenylpropan-2-yl 2-bromoacetate (15.2 g,59.2 mmol), sodium iodide (17.7 g, 0.118 mmol), and cesium carbonate(38.4 g, 0.118 mmol) are dissolved in DMF (200 mL) and stirred at 25° C.for 4 h. The reaction mixture is quenched with water (500 mL), extractedwith DCM (2×200 mL), the combined organic layers washed with water(4×200 mL), concentrated to a viscous oil and precipitated from MTBE (1L) to afford the title compound as a white solid.

Example 8

5-(4-methoxy-3-(2-oxo-2-((2-oxotetrahydrofuran-3-yl)oxy)ethyl)phenyl)-dibenzothiopheniumiodide

5-(3-(carboxymethyl)-4-methoxyphenyl)-dibenzothiophenium iodide (50 g,105 mmol), 3-bromodihydrofuran-2(3H)-one (17.3 g, 105 mmol), and cesiumcarbonate (68.3 g, 210 mmol) are dissolved in DMF (400 mL) and stirredat 25° C. for 4 h. The reaction mixture is quenched with water (1 L),extracted with DCM (2×400 mL), the combined organic layers washed withwater (4×500 mL), concentrated to a viscous oil and precipitated fromMTBE (2 L) to afford the title compound as a white solid.

Example 9

(4-(2-methoxy-2-oxoethyl)naphthalen-1-yl)diphenylsulfonium1,1-difluoro-2-(methacryloyloxy)ethanesulfonate

(4-(2-methoxy-2-oxoethyl)naphthalen-1-yl)diphenylsulfonium iodide (5 g,9.76 mmol) and triethylammonium1,1-difluoro-2-(methacryloyloxy)ethanesulfonate (3.40 g, 10.2 mmol) aredissolved in DCM (200 mL) and water (200 mL) and stirred at 25° C.overnight. The layers are separated, the organic layer washed with water(10×150 mL), and concentrated under reduced pressure to afford the titlecompound as a white solid.

Example 10 Preparation of Polymer with Acid Generator Units

Heel solution was made by dissolving 2-phenylpropan-2-yl methacrylate(0.39 g), 2-oxotetrahydrofuran-3-yl methacrylate (0.33 g),3,5-bis(1,1,1,3,3,3-hexafluoro-2-hydroxypropan-2-yl)cyclohexylmethacrylate (0.57 g) and5-(4-(2-(1-ethylcyclopentyloxy)-2-oxoethoxy)-3,5-dimethylphenyl)-5H-dibenzo[b,d]thiophenium1,1-difluoro-2-(methacryloyloxy)ethanesulfonate (0.31 g) in 12.81 gacetonitrile/tetrahydrofuran (2/1 v/v). Feed solution was prepared bydissolving 2-phenylpropan-2-yl methacrylate (185.54 g, 0.967 mol),2-oxotetrahydrofuran-3-yl methacrylate (204.27 g, 1.26 mol),3,5-bis(1,1,1,3,3,3-hexafluoro-2-hydroxypropan-2-yl)cyclohexylmethacrylate (127.98 g, 0.29 mol) and5-(4-(2-(1-ethylcyclopentyloxy)-2-oxoethoxy)-3,5-dimethylphenyl)-5H-dibenzo[b,d]thiophenium1,1-difluoro-2-(methacryloyloxy)ethanesulfonate (81.5 g, 0.132 mol) in606 g ethyl lactate:γ-butryl lactone (30/70 v/v). Initiator solution wasprepared by dissolving 65.96 g initiator (V-65) in 66 gacetonitrile/tetrahydrofuran (2/1 v/v). The polymerization was carriedout in a 2 L 3-neck round bottom flask fitted with a water condenser anda thermometer to monitor the reaction in the flask. The contents werestirred using an overhead stirrer. The reactor was charged with the heelsolution and the contents were heated to 75° C. The feed solution andthe initiator solution were fed into the reactor using syringe pump overa 4 hour time period. The contents were then stirred for additional 2hours, whereby, the reaction was quenched using hydroquinone (2.0 g).The contents were cooled to room temperature and precipitated twice outof 10× (by weight) IPE/MeOH 95/5 (w/w). The polymer obtained was driedin vacuuo after each precipitation step at 50° C. for 24 hours to yield500 g polymer.

Example 11 Preparation of Polymer with Acid Generator Units

The same process used for Example 10 was used in the preparation ofpolymer, except 5-phenyl-5H-dibenzo[b,d]thiophenium1,1-difluoro-2-(methacryloyloxy)ethanesulfonate was used in place of5-(4-(2-(1-ethylcyclopentyloxy)-2-oxoethoxy)-3,5-dimethylphenyl)-5H-dibenzo[b,d]thiophenium1,1-difluoro-2-(methacryloyloxy)ethanesulfonate.

Example 12 Preparation of Polymer with Acid Generator Units

The same process used for Example 10 was used in the preparation ofpolymer, except 5-(4-(tert-butyl)phenyl)-5H-dibenzo[b,d]thiophen-5-ium1,1-difluoro-2-(methacryloyloxy)ethanesulfonate was used in place of5-(4-(2-(1-ethylcyclopentyloxy)-2-oxoethoxy)-3,5-dimethylphenyl)-5H-dibenzo[b,d]thiophenium1,1-difluoro-2-(methacryloyloxy)ethanesulfonate.

Example 13 Preparation and Processing of Photoresist Composition

A positive-tone photoresist composition was prepared by combiningcomponent 1, 7.952 g of a 10 wt % solution of the polymer from Example10 in ethyl lactate; component 2, 9.289 g of a 2 wt % solution of theacid generator5-(4-(2-(1-ethylcyclopentyloxy)-2-oxoethoxy)-3,5-dimethylphenyl)-5H-dibenzo[b,d]thiophenium3-hydroxyadamantane-acetoxy-1,1,2,2-tetrafluorobutane-1-sulfonate inethyl lactate; component 3, 0.932 g of a 0.5 wt % solution oftetrakis(2-hydroxypropyl)ethylenediamine in ethyl lactate; component 4,0.680 g of a 2 wt % solution of(1r,3s,5R,7S)-3-hydroxyadamantane-1-carboxylic acid,5-(4-(2-((1-ethylcyclopentyl)oxy)-2-oxoethoxy)-3,5-dimethylphenyl)-5H-dibenzo[b,d]thiophen-5-iumsalt in ethyl lactate; component 5, 0.159 g of a 0.5 wt % solution offluorinated surfactant (Omnova PF656) in ethyl lactate; component 6,9.287 g of ethyl lactate; and component 7, 11.700 g of2-hydroxyisobutyric acid methyl ester. The formulated resist was passedthrough a 0.01 μm PTFE filter. The thus prepared resist is spin coatedonto a silicon wafer, soft baked to remove carrier solvent and exposedthrough a photomask to EUV radiation. The imaged resist layer is thenbaked at 110° C. for 60 seconds and then developed with an aqueousalkaline composition.

Examples 14-20 Photoresist Compositions

Photoresist compositions were prepared and processed according toExample 13 with the appropriate changes according to Table 1:

TABLE 1 Photoresist components: In Table 1, the referenced charactersindicate the following according to Table 2 with values in brackets [ ]indicating the amount in grams of the component added in accordance withExample 13 or are direct references to synthetic examples, again withvalues in brackets [ ] indicating the amount in grams of the componentadded in accordance with Example 13. When there are no referencecharacters or corresponding examples, the component is the same as thecorresponding component of Example 13. All samples were processedaccording to Example 13. Example: Component 1 Component 2 Component 3Component 4 Component 5 Component 6 Component 7 14 Example 12 Example 4[0.587] 2-4 [0.196] [12.028] [14.041] [9.789] [12.706] [0.653] 15Example 11 Example 4 [0.588] 2-1 [0.196] [12.069] [14.040] [9.799][12.724] [0.583] 16 Example 11 2-2 [0.594] [0.589] [0.198] [12.440][14.034] [9.892] [12.254] 17 Example 10 [94.235] [13.304]  [1.109][48.170] [87.750] [55.432] 18 Example 11 2-3 [0.614] 2-1 [0.206][13.543] [14.625] [10.322] [10.071] [0.619] 19 Example 12 2-3 [0.606]2-1 [0.202] [12.683] [14.625] [10.103] [11.114] [0.667] 20 Example 11[0.374] [0.249] [22.655] [14.253] [12.469]

TABLE 2 Key for Table 1: Character Name 2-1(1r,3s,5R,7S)-3-hydroxyadamantane-1-carboxylic acid, 5-phenyl-5H-dibenzo[b,d]thiophen-5-ium salt 2-25-(3,5-dimethyl-4-(2-(((1R,3S,5r,7r-2-methyladamantan-2-yl)oxy)-2-oxoethoxy)phenyl)-5H-dibenzo[b,d]thiophen- 5-ium1,1,2,2-tetrafluoro-4-(((1r,3s,5R,7S)-3-hydroxyadamantane-1-carbonyl)oxy)butane-1-sulfonate 2-35-(4-(tert-butyl)phenyl)-5H-dibenzo[b,d]thiophen-5- ium1,1,2,2-tetrafluoro-4-(((1r,3s,5R,7S)-3-hydroxyadamantane-1-carbonyl)oxy)butane-1-sulfonate 2-4(1r,3s,5R,7S)-3-hydroxyadamantane-1-carboxylic acid, 5-(4-(tert-butyl)phenyl)-5H-dibenzo[b,d]thiophen-5-ium salt

Example 21 Lithographic Evaluation

For the tables below, Esize, CDU, LWR and EL % are all evaluated in thefollowing way: There are multiple comparative examples for thecomparison of the experimental data sets. The experimental data sets arenormalized to 1 and consequently designated with “⋄”; very poor metrics,comparative examples which underperform the experimental data by morethan 20%, are designated with “Δ”; poor metrics, those which representsat least a 10% underperformance relative to the respective comparative,are designated with “□”; fair metrics, those which represents between 0%and 10% underperformance relative to the respective comparative, aredesignated with “▪”; and good metrics, those which represent <0%improvement relative to the experimental data, are designated with “●”;

E-size and exposure latitude % (EL %) were calculated from criticaldimension (CD) data through dose and focus (FEM) with 10% CD boundariesrestricted to 100 nm depth of focus (DoF). CDU is the calculated 3 Sigmafor 10 FOV measuring 36 CH for each FOV, all taken within bestexposure/best focus.

TABLE 3 Example Esize (mJ) CDU (nm) CER (nm) EL % 14 ⋄ ⋄ ⋄ ⋄ 15 □ □ □ Δ13 ● Δ ▪ Δ 18 ● □ □ Δ 19 □ Δ □ Δ

TABLE 4 Example Esize (mJ) LWR (nm) EL % 15 ⋄ ⋄ ⋄ 16 ▪ ▪ ▪ 17 □ □ □ 13 ▪▪ ● 18 ● ▪ Δ 20 ● Δ ΔAs seen in Tables 3 and 4, photoresists that comprise a photoacidgenerator (PAG) of the invention exhibit improved lithographicperformance.

What is claimed is:
 1. An acid generator that comprises a structure ofFormula (I):

wherein: Z is a counter anion; X is sulfur or iodine; R is optionallysubstituted alkyl, optionally substituted heteroalkyl, or optionallysubstituted alicyclic; R′ and R″ are the same or different optionallysubstituted heteroalkyl, optionally substituted alicyclic, optionallysubstituted heteroalicyclic, optionally substituted carbocyclic aryl oroptionally substituted heteroaromatic, provided that if X is iodine, oneof R′ and R″ is absent; and A is an optionally substituted carbocyclicaryl or optionally substituted heteroaromatic group, and Z⁻comprises astructure of Formula (II):

wherein: Y is a sulfonate, carboxylate, sulfate, sulfamate, or the anionof a sulfonamide or sulfonimide; R′″ is a hydrogen or non-hydrogensubstituent; and W and W′ are independently chosen from hydrogen,fluorine, cyano, optionally substituted alkyl and optionally substitutedaryl, wherein two or more of W, W′ and R′″ together optionally form aring; provided that when W and W′ are each independently fluorine orperfluoroalkyl, Y is chosen from carboxylate, sulfate, sulfamate, or theanion of a sulfonamide or sulfonimide.
 2. An acid generator of claim 1wherein the acid generator comprises a polymerizable moiety.
 3. Aphotoresist composition comprising one or more acid generators ofclaim
 1. 4. A method for providing a photoresist relief image,comprising: a) applying a coating layer of a photoresist composition ofclaim 3 on a substrate; and b) exposing the photoresist compositionlayer to activating radiation and developing the exposed photoresistcomposition coating layer.
 5. The acid generator of claim 1 wherein X issulfur.
 6. The acid generator of claim 1 wherein X is iodine.
 7. Theacid generator of claim 1 wherein R′ and R″ are the same or differentoptionally substituted heteroalkyl, optionally substituted alicyclic,optionally substituted heteroalicyclic, optionally substitutedcarbocyclic aryl.
 8. An acid generator that comprises a structure ofFormula (V):

wherein: Z is a counter anion; R₂ is H or is a group comprising anacid-labile moiety; each T, each T′ and each T″ are the same ordifferent non-hydrogen substituent, wherein either of T and T″ or T andT′ are capable of joining to form a ring; n is 0, 1, 2, 3 or 4; n′ andn″ are each independently 0, 1, 2, 3, 4 or 5; J represents a chemicalbond, or a group capable of covalently linking B and C; D and D′ are thesame or different and are each hydrogen or a non-hydrogen substituent,and optionally taken together may form a ring; and A, B, and C are thesame or different optionally substituted carbocyclic aryl or optionallysubstituted heteroaromatic group.
 9. A photoresist compositioncomprising one or more acid generators of claim
 8. 10. A method forproviding a photoresist relief image, comprising: a) applying a coatinglayer of a photoresist composition of claim 9 on a substrate; and b)exposing the photoresist composition layer to activating radiation anddeveloping the exposed photoresist composition coating layer.
 11. Anacid generator that comprises a structure of Formula (I):R′—X⁺—A—CH₂—C(═O)—O—R Z⁻  (I) wherein: Z is a counter anion; X isiodine; R is a non-hydrogen substituent; R′ is an optionally substitutedheteroalkyl, optionally substituted alicyclic, optionally substitutedheteroalicyclic, optionally substituted carbocyclic aryl or optionallysubstituted heteroaromatic; and A is an optionally substitutedcarbocyclic aryl or optionally substituted heteroaromatic group.
 12. Aphotoresist composition comprising one or more acid generators of claim11.
 13. A method for providing a photoresist relief image, comprising:a) applying a coating layer of a photoresist composition of claim 12 ona substrate; and b) exposing the photoresist composition layer toactivating radiation and developing the exposed photoresist compositioncoating layer.
 14. An acid generator that comprises a structure ofFormula (I):R′—X⁺—A—CH₂—C(═O)—O—R Z⁻  (I) wherein: Z is a counter anion; X isiodine; R is optionally substituted alkyl, optionally substitutedheteroalkyl, or optionally substituted alicyclic; R′ is a substitutedheteroalkyl, optionally substituted alicyclic, optionally substitutedheteroalicyclic, optionally substituted carbocyclic aryl or optionallysubstituted heteroaromatic; and A is an optionally substitutedcarbocyclic aryl or optionally substituted heteroaromatic group.
 15. Aphotoresist composition comprising one or more acid generators of claim14.
 16. A method for providing a photoresist relief image, comprising:a) applying a coating layer of a photoresist composition of claim 15 ona substrate; and b) exposing the photoresist composition layer toactivating radiation and developing the exposed photoresist compositioncoating layer.